With the specific red cell adherence (SRCA) test we demonstrated the loss of A, B, and H antigens in carcinomas of the cervix, bronchus, stomach, pancreas, fallopian tubes and urinary bladder. The loss of the antigens paralleled and frequently preceded the histologically demonstrable anaplasia and also preceded the formation of distant metastases, thus permitting the conclusion that the SRCA test may have diagnostic and prognostic merits. These investigations were retrospective and based exclusively on the study of stored tissues. To overcome this limitation we have begun prospective studies of benign lesions and of carcinoma of the cervix. We receive paraffin sections as unknowns and compare clinical data and histologic findings with the results of the test. We plan to extend our studies to carcinomas of the ovary, rectum, gallbladder, larynx, kidney pelvis, ureter, and vagina. Using a quantitative technic which we developed, we are planning to study the concentration of the three antigens in the normal tissues of the newborn, of the middle-aged and the old, and to compare the results with the known changes in the antigens of erythrocytes. This may throw light on the increased incidence of some carcinomas in the aged.